1curs_attr(3X) curs_attr(3X)
2
6 attr_get, wattr_get, attr_set, wattr_set, attr_off, wattr_off, attr_on,
7 wattr_on, attroff, wattroff, attron, wattron, attrset, wattrset, chgat,
8 wchgat, mvchgat, mvwchgat, color_set, wcolor_set, standend, wstandend,
9 standout, wstandout - curses character and window attribute control
10 routines
11
13 #include <curses.h>
14 int attr_get(attr_t *attrs, short *pair, void *opts);
16 int wattr_get(WINDOW *win, attr_t *attrs, short *pair, void *opts);
17 int attr_set(attr_t attrs, short pair, void *opts);
18 int wattr_set(WINDOW *win, attr_t attrs, short pair, void *opts);
19 int attr_off(attr_t attrs, void *opts);
21 int wattr_off(WINDOW *win, attr_t attrs, void *opts);
22 int attr_on(attr_t attrs, void *opts);
23 int wattr_on(WINDOW *win, attr_t attrs, void *opts);
24 int attroff(int attrs);
26 int wattroff(WINDOW *win, int attrs);
27 int attron(int attrs);
28 int wattron(WINDOW *win, int attrs);
29 int attrset(int attrs);
30 int wattrset(WINDOW *win, int attrs);
31 int chgat(int n, attr_t attr, short pair, const void *opts);
33 int wchgat(WINDOW *win,
34 int n, attr_t attr, short pair, const void *opts);
35 int mvchgat(int y, int x,
36 int n, attr_t attr, short pair, const void *opts);
37 int mvwchgat(WINDOW *win, int y, int x,
38 int n, attr_t attr, short pair, const void *opts);
39 int color_set(short pair, void* opts);
41 int wcolor_set(WINDOW *win, short pair, void* opts);
42 int standend(void);
44 int wstandend(WINDOW *win);
45 int standout(void);
46 int wstandout(WINDOW *win);
47
49 These routines manipulate the current attributes of the named window,
50 which then apply to all characters that are written into the window
51 with waddch, waddstr and wprintw. Attributes are a property of the
52 character, and move with the character through any scrolling and in‐
53 sert/delete line/character operations. To the extent possible, they
54 are displayed as appropriate modifications to the graphic rendition of
55 characters put on the screen.
56 These routines do not affect the attributes used when erasing portions
58 of the window. See curs_bkgd(3X) for functions which modify the at‐
59 tributes used for erasing and clearing.
60 Routines which do not have a WINDOW* parameter apply to stdscr. For
62 example, attr_set is the stdscr variant of wattr_set.
63 Window attributes
65 There are two sets of functions:
66 • functions for manipulating the window attributes and color: wat‐
68 tr_set and wattr_get.
69 • functions for manipulating only the window attributes (not color):
71 wattr_on and wattr_off.
72 The wattr_set function sets the current attributes of the given window
74 to attrs, with color specified by pair.
75 Use wattr_get to retrieve attributes for the given window.
77 Use attr_on and wattr_on to turn on window attributes, i.e., values
79 OR'd together in attr, without affecting other attributes. Use at‐
80 tr_off and wattr_off to turn off window attributes, again values OR'd
81 together in attr, without affecting other attributes.
82 Legacy window attributes
84 The X/Open window attribute routines which set or get, turn on or off
85 are extensions of older routines which assume that color pairs are OR'd
86 into the attribute parameter. These newer routines use similar names,
87 because X/Open simply added an underscore (_) for the newer names.
88 The int datatype used in the legacy routines is treated as if it is the
90 same size as chtype (used by addch(3X)). It holds the common video at‐
91 tributes (such as bold, reverse), as well as a few bits for color.
92 Those bits correspond to the A_COLOR symbol. The COLOR_PAIR macro pro‐
93 vides a value which can be OR'd into the attribute parameter. For ex‐
94 ample, as long as that value fits into the A_COLOR mask, then these
95 calls produce similar results:
96 attrset(A_BOLD | COLOR_PAIR(pair));
98 attr_set(A_BOLD, pair, NULL);
99 However, if the value does not fit, then the COLOR_PAIR macro uses only
101 the bits that fit. For example, because in ncurses A_COLOR has eight
102 (8) bits, then COLOR_PAIR(259) is 4 (i.e., 259 is 4 more than the limit
103 255).
104 The PAIR_NUMBER macro extracts a pair number from an int (or chtype).
106 For example, the input and output values in these statements would be
107 the same:
108 int value = A_BOLD | COLOR_PAIR(input);
110 int output = PAIR_NUMBER(value);
111 The attrset routine is a legacy feature predating SVr4 curses but kept
113 in X/Open Curses for the same reason that SVr4 curses kept it: compati‐
114 bility.
115 The remaining attr* functions operate exactly like the corresponding
117 attr_* functions, except that they take arguments of type int rather
118 than attr_t.
119 There is no corresponding attrget function as such in X/Open Curses,
121 although ncurses provides getattrs (see curs_legacy(3X)).
122 Change character rendition
124 The routine chgat changes the attributes of a given number of charac‐
125 ters starting at the current cursor location of stdscr. It does not
126 update the cursor and does not perform wrapping. A character count of
127 -1 or greater than the remaining window width means to change at‐
128 tributes all the way to the end of the current line. The wchgat func‐
129 tion generalizes this to any window; the mvwchgat function does a cur‐
130 sor move before acting.
131 In these functions, the color pair argument is a color-pair index (as
133 in the first argument of init_pair, see curs_color(3X)).
134 Change window color
136 The routine color_set sets the current color of the given window to the
137 foreground/background combination described by the color pair parame‐
138 ter.
139 Standout
141 The routine standout is the same as attron(A_STANDOUT). The routine
142 standend is the same as attrset(A_NORMAL) or attrset(0), that is, it
143 turns off all attributes.
144 X/Open does not mark these “restricted”, because
146 • they have well established legacy use, and
148 • there is no ambiguity about the way the attributes might be com‐
150 bined with a color pair.
151
153 The following video attributes, defined in <curses.h>, can be passed to
154 the routines attron, attroff, and attrset, or OR'd with the characters
155 passed to addch (see curs_addch(3X)).
156 Name Description
158 ─────────────────────────────────────────────────────────────────
159 A_NORMAL Normal display (no highlight)
160 A_STANDOUT Best highlighting mode of the terminal.
161 A_UNDERLINE Underlining
162 A_REVERSE Reverse video
163 A_BLINK Blinking
164 A_DIM Half bright
165 A_BOLD Extra bright or bold
166 A_PROTECT Protected mode
167 A_INVIS Invisible or blank mode
168 A_ALTCHARSET Alternate character set
169 A_ITALIC Italics (non-X/Open extension)
170 A_CHARTEXT Bit-mask to extract a character
171 A_COLOR Bit-mask to extract a color (legacy routines)
172 These video attributes are supported by attr_on and related functions
174 (which also support the attributes recognized by attron, etc.):
175 Name Description
177 ─────────────────────────────────────────
178 WA_HORIZONTAL Horizontal highlight
179 WA_LEFT Left highlight
180 WA_LOW Low highlight
181 WA_RIGHT Right highlight
182 WA_TOP Top highlight
183 WA_VERTICAL Vertical highlight
184 The return values of many of these routines are not meaningful (they
186 are implemented as macro-expanded assignments and simply return their
187 argument). The SVr4 manual page claims (falsely) that these routines
188 always return 1.
189
191 These functions may be macros:
192 attroff, wattroff, attron, wattron, attrset, wattrset, standend
194 and standout.
195 Color pair values can only be OR'd with attributes if the pair number
197 is less than 256. The alternate functions such as color_set can pass a
198 color pair value directly. However, ncurses ABI 4 and 5 simply OR this
199 value within the alternate functions. You must use ncurses ABI 6 to
200 support more than 256 color pairs.
201
203 X/Open Curses is largely based on SVr4 curses, adding support for
204 “wide-characters” (not specific to Unicode). Some of the X/Open dif‐
205 ferences from SVr4 curses address the way video attributes can be ap‐
206 plied to wide-characters. But aside from that, attrset and attr_set
207 are similar. SVr4 curses provided the basic features for manipulating
208 video attributes. However, earlier versions of curses provided a part
209 of these features.
210 As seen in 2.8BSD, curses assumed 7-bit characters, using the eighth
212 bit of a byte to represent the standout feature (often implemented as
213 bold and/or reverse video). The BSD curses library provided functions
214 standout and standend which were carried along into X/Open Curses due
215 to their pervasive use in legacy applications.
216 Some terminals in the 1980s could support a variety of video at‐
218 tributes, although the BSD curses library could do nothing with those.
219 System V (1983) provided an improved curses library. It defined the A_
220 symbols for use by applications to manipulate the other attributes.
221 There are few useful references for the chronology.
222 Goodheart's book UNIX Curses Explained (1991) describes SVr3 (1987),
224 commenting on several functions:
225 • the attron, attroff, attrset functions (and most of the functions
227 found in SVr4 but not in BSD curses) were introduced by System V,
228 • the alternate character set feature with A_ALTCHARSET was added in
230 SVr2 and improved in SVr3 (by adding acs_map[]),
231 • start_color and related color-functions were introduced by System
233 V.3.2,
234 • pads, soft-keys were added in SVr3, and
236 Goodheart did not mention the background character or the cchar_t type.
238 Those are respectively SVr4 and X/Open features. He did mention the A_
239 constants, but did not indicate their values. Those were not the same
240 in different systems, even for those marked as System V.
241 Different Unix systems used different sizes for the bit-fields in
243 chtype for characters and colors, and took into account the different
244 integer sizes (32-bit versus 64-bit).
245 This table showing the number of bits for A_COLOR and A_CHARTEXT was
247 gleaned from the curses header files for various operating systems and
248 architectures. The inferred architecture and notes reflect the format
249 and size of the defined constants as well as clues such as the alter‐
250 nate character set implementation. A 32-bit library can be used on a
251 64-bit system, but not necessarily the reverse.
252 Year System Arch Color Char Notes
254 ────────────────────────────────────────────────────────────────
255 1992 Solaris 5.2 32 6 17 SVr4 curses
256 1992 HPUX 9 32 no 8 SVr2 curses
257 1992 AIX 3.2 32 no 23 SVr2 curses
258 1994 OSF/1 r3 32 no 23 SVr2 curses
259 1995 HP-UX 10.00 32 6 16 SVr3 “curses_colr”
260 1995 HP-UX 10.00 32 6 8 SVr4, X/Open curses
261 1995 Solaris 5.4 32/64 7 16 X/Open curses
262 1996 AIX 4.2 32 7 16 X/Open curses
263 1996 OSF/1 r4 32 6 16 X/Open curses
264 1997 HP-UX 11.00 32 6 8 X/Open curses
266 2000 U/Win 32/64 7/31 16 uses chtype
267 Notes:
269 Regarding HP-UX,
271 • HP-UX 10.20 (1996) added support for 64-bit PA-RISC processors
273 in 1996.
274 • HP-UX 10.30 (1997) marked “curses_colr” obsolete. That version
276 of curses was dropped with HP-UX 11.30 in 2006.
277 Regarding OSF/1 (and Tru64),
279 • These used 64-bit hardware. Like ncurses, the OSF/1 curses in‐
281 terface is not customized for 32-bit and 64-bit versions.
282 • Unlike other systems which evolved from AT&T code, OSF/1 provid‐
284 ed a new implementation for X/Open curses.
285 Regarding Solaris,
287 • The initial release of Solaris was in 1992.
289 • The xpg4 (X/Open) curses was developed by MKS from 1990 to 1995.
291 Sun's copyright began in 1996.
292 • Sun updated the X/Open curses interface after 64-bit support was
294 introduced in 1997, but did not modify the SVr4 curses inter‐
295 face.
296 Regarding U/Win,
298 • Development of the curses library began in 1991, stopped in
300 2000.
301 • Color support was added in 1998.
303 • The library uses only chtype (no cchar_t).
305 Once X/Open curses was adopted in the mid-1990s, the constraint of a
307 32-bit interface with many colors and wide-characters for chtype became
308 a moot point. The cchar_t structure (whose size and members are not
309 specified in X/Open Curses) could be extended as needed.
310 Other interfaces are rarely used now:
312 • BSD curses was improved slightly in 1993/1994 using Keith Bostic's
314 modification to make the library 8-bit clean for nvi(1). He moved
315 standout attribute to a structure member.
316 The resulting 4.4BSD curses was replaced by ncurses over the next
318 ten years.
319 • U/Win is rarely used now.
321
323 This implementation provides the A_ITALIC attribute for terminals which
324 have the enter_italics_mode (sitm) and exit_italics_mode (ritm) capa‐
325 bilities. Italics are not mentioned in X/Open Curses. Unlike the oth‐
326 er video attributes, A_ITALIC is unrelated to the set_attributes capa‐
327 bilities. This implementation makes the assumption that exit_attri‐
328 bute_mode may also reset italics.
329 Each of the functions added by XSI Curses has a parameter opts, which
331 X/Open Curses still (after more than twenty years) documents as re‐
332 served for future use, saying that it should be NULL. This implementa‐
333 tion uses that parameter in ABI 6 for the functions which have a color-
334 pair parameter to support extended color pairs:
335 • For functions which modify the color, e.g., wattr_set and wattr_on,
337 if opts is set it is treated as a pointer to int, and used to set
338 the color pair instead of the short pair parameter.
339 • For functions which retrieve the color, e.g., wattr_get, if opts is
341 set it is treated as a pointer to int, and used to retrieve the
342 color pair as an int value, in addition to retrieving it via the
343 standard pointer to short parameter.
344 • For functions which turn attributes off, e.g., wattr_off, the opts
346 parameter is ignored except except to check that it is NULL.
347
349 These functions are supported in the XSI Curses standard, Issue 4. The
350 standard defined the dedicated type for highlights, attr_t, which was
351 not defined in SVr4 curses. The functions taking attr_t arguments were
352 not supported under SVr4.
353 Very old versions of this library did not force an update of the screen
355 when changing the attributes. Use touchwin to force the screen to
356 match the updated attributes.
357 The XSI Curses standard states that whether the traditional functions
359 attron/attroff/attrset can manipulate attributes other than A_BLINK,
360 A_BOLD, A_DIM, A_REVERSE, A_STANDOUT, or A_UNDERLINE is “unspecified”.
361 Under this implementation as well as SVr4 curses, these functions cor‐
362 rectly manipulate all other highlights (specifically, A_ALTCHARSET,
363 A_PROTECT, and A_INVIS).
364 XSI Curses added these entry points:
366 attr_get, attr_on, attr_off, attr_set, wattr_on, wattr_off, wat‐
368 tr_get, wattr_set
369 The new functions are intended to work with a new series of highlight
371 macros prefixed with WA_. The older macros have direct counterparts in
372 the newer set of names:
373 Name Description
375 ────────────────────────────────────────────────────────────
376 WA_NORMAL Normal display (no highlight)
377 WA_STANDOUT Best highlighting mode of the terminal.
378 WA_UNDERLINE Underlining
379 WA_REVERSE Reverse video
380 WA_BLINK Blinking
381 WA_DIM Half bright
382 WA_BOLD Extra bright or bold
383 WA_ALTCHARSET Alternate character set
384 XSI curses does not assign values to these symbols, nor does it state
386 whether or not they are related to the similarly-named A_NORMAL, etc.:
387 • The XSI curses standard specifies that each pair of corresponding
389 A_ and WA_-using functions operates on the same current-highlight
390 information.
391 • However, in some implementations, those symbols have unrelated val‐
393 ues.
394 For example, the Solaris xpg4 (X/Open) curses declares attr_t to be
396 an unsigned short integer (16-bits), while chtype is a unsigned in‐
397 teger (32-bits). The WA_ symbols in this case are different from
398 the A_ symbols because they are used for a smaller datatype which
399 does not represent A_CHARTEXT or A_COLOR.
400 In this implementation (as in many others), the values happen to be
402 the same because it simplifies copying information between chtype
403 and cchar_t variables.
404 • Because ncurses's attr_t can hold a color pair (in the A_COLOR
406 field), a call to wattr_on, wattr_off, or wattr_set may alter the
407 window's color. If the color pair information in the attribute pa‐
408 rameter is zero, no change is made to the window's color.
409 This is consistent with SVr4 curses; X/Open Curses does not specify
411 this.
412 The XSI standard extended conformance level adds new highlights A_HORI‐
414 ZONTAL, A_LEFT, A_LOW, A_RIGHT, A_TOP, A_VERTICAL (and corresponding
415 WA_ macros for each). As of August 2013, no known terminal provides
416 these highlights (i.e., via the sgr1 capability).
417
419 All routines return the integer OK on success, or ERR on failure.
420 X/Open does not define any error conditions.
422 This implementation
424 • returns an error if the window pointer is null.
426 • returns an error if the color pair parameter for wcolor_set is out‐
428 side the range 0..COLOR_PAIRS-1.
429 • does not return an error if either of the parameters of wattr_get
431 used for retrieving attribute or color-pair values is NULL.
432 Functions with a “mv” prefix first perform a cursor movement using
434 wmove, and return an error if the position is outside the window, or if
435 the window pointer is null.
436
438 curses(3X), curs_addch(3X), curs_addstr(3X), curs_bkgd(3X),
439 curs_printw(3X), curs_variables(3X)
440 curs_attr(3X)